The Astroviridae are non-enveloped, small (28 to 30 nm in diameter), single-stranded positive sense RNA viruses whose genomes range in size from 6.4 kb to 7.3 kb. The genome includes three open reading frames (ORFs) designated ORF1a, ORF1b, and ORF2. ORF1a encodes the non-structural polyprotein 1a while the longer ORF1b encodes polyprotein 1ab including the RNA dependent RNA polymerase (RdRp) expressed through a ribosomal frameshift at the ORF1a/1b junction mediated by a slippery polyA sequence. ORF2 encodes the viral structural polyprotein (Mendez & Arias (2007) Astroviridae. In Fields Virology, pp. 981-1000. Edited by D. M. Knipe and P. M. Howley. Philadelphia: Lippincott Williams & Wilkins; Monroe et al. (2005) Astroviridae. In Virus Taxonomy. Eighth Report of the International Committee on Taxonomy of Viruses, pp. 859-64. Edited by C. M. Fauquet, M. A. Mayo, J. Maniloff, U. Desselberger and L. A. Ball. Amsterdam Elsevier Academic Press).
The family Astroviridae consists so far of two genera, Avastrovirus and Mamastrovirus, that infects avian and mammalian hosts respectively. Astroviruses, transmitted through the fecal-oral route cause gastroenteritis in mammalian and avian species including humans, calves, piglets, sheep, minks, dogs, cats, mice, chickens, and turkeys (Jonassen et al. (2001) J. Gen. Virol. 82:1061-67; Jonassen et al. (2003) Virus Res. 91:195-201). All eight known human astroviruses serotypes belonging to the first identified human astrovirus species (HAstV) have been associated with gastroenteritis (Clark & McKendrick (2004) Curr. Opin. Infect. Dis. 17:461-69; Fodha et al. (2006) J. Med. Virol. 78:1198-1203; Gabbay et al. (2007) Mem. Inst. Oswaldo Cruz 102:531-34; Jin et al. (2009) J. Clin. Virol: 44:238-41; Tayeb et al. (2008) J. Med. Virol. 80:1919-29). Clinical symptoms of HAstV infection in humans usually last between two and four days and consist of watery diarrhea and, less commonly, vomiting, headache, fever, abdominal pains, and anorexia (Mendez & Arias (2007) Astroviridae. In Fields Virology, pp. 981-1000. Edited by D. M. Knipe and P. M. Howley. Philadelphia: Lippincott Williams & Wilkins; Monroe et al. (2005) Astroviridae. In Virus Taxonomy. Eighth Report of the International Committee on Taxonomy of Viruses, pp. 859-64. Edited by C. M. Fauquet, M. A. Mayo, J. Maniloff, U. Desselberger and L. A. Ball. Amsterdam Elsevier Academic Press). HAstV can also cause significant disease in the elderly and in immunocompromised patients (Liste et al. (2000) J. Clin. Microbial. 38:2873-77). Recently a second species of astrovirus was found in a child with diarrhea and named AstV-MLB (Finkbeiner et al. (2008) Virol. J. 5:117).
Group reactive or pan-PCR approaches have been successfully used to identify new viruses in humans (Oberste et al. (2005) J. Gen. Viral. 86:445-51; Oberste et al. (2004) J. Gen. Virol. 85:3205-3212), animals (Atkins et al. (2009) Vet. Microbial. 136:160-65; Nollens et al. (2008) Vet. Microbial. 128:231-42; Smith et al. (2008) Vet. Microbial. 129:236-45; Wellehan et al. (2008) Vet. Microbial. 127:249-57; Wellehan et al. (2009) Vet. Microbial. 133:34-42; Zhu et al. (2009) J. Gen. Virol. 90:883-87) and environmental samples (Culley et al. (2003) Nature 424:1054-57; Culley et al. (2007) Virol. J. 4:69; Culley & Steward (2007) Appl. Environ. Microbial. 73:5937-44).
Despite the known pathogenicity of astroviruses and the urgent need for methods to prevent, diagnose and treat astrovirus infections, other divergent human astroviruses have not yet been identified. Therefore, a need exists to detect divergent human astroviruses and to provide a method to diagnose, prevent and treat astroviruses infection. Moreover, there exists a need to provide methods to identify astroviruses antiviral compounds.